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		<h1>shell 练习-删除文本中的字母</h1>
	
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		<span class="article__date">2017-10-12</span><br />
		
		
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			  	<a class="article__tag-link" href="/tags/shell练习/">shell练习</a>
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		<p>使用sed实现，把一个文本文档中的前5行中包含字母的行删除掉。</p>
<figure class="highlight bash"><table><tr><td class="gutter"><pre><div class="line">1</div></pre></td><td class="code"><pre><div class="line">head -5 1.txt|sed <span class="string">'/[a-Z]/d'</span></div></pre></td></tr></table></figure>
<p>把一个文本文档的前5行中包含字母的行删除掉，同时把6到10行中的全部字母删除掉。</p>
<p>假设文本名字叫做1.txt，并且文本行数大于10，脚本如下</p>
<figure class="highlight bash"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div></pre></td><td class="code"><pre><div class="line"><span class="meta">#!/bin/bash</span></div><div class="line"><span class="comment">##先获取该文本的行数</span></div><div class="line">nu=`wc -l 1.txt |awk <span class="string">'&#123;print $1&#125;'</span>`</div><div class="line"><span class="comment">##对前5行进程处理</span></div><div class="line"><span class="keyword">for</span> i <span class="keyword">in</span> `seq 1 5`</div><div class="line"><span class="keyword">do</span> </div><div class="line">    <span class="comment">##使用sed把每一行的内容赋值给变量</span></div><div class="line">    l=`sed -n <span class="string">"<span class="variable">$i</span>"</span>p 1.txt`</div><div class="line">    <span class="comment">##用grep 判定是否匹配字母,-v取反，-q不输出内容</span></div><div class="line">    <span class="keyword">if</span> <span class="built_in">echo</span> <span class="variable">$l</span> |grep -vq <span class="string">'[a-zA-Z]'</span></div><div class="line">    <span class="keyword">then</span></div><div class="line">	<span class="built_in">echo</span> <span class="variable">$l</span></div><div class="line">    <span class="keyword">fi</span></div><div class="line"><span class="keyword">done</span></div><div class="line"><span class="comment">##对6-10行做删除字母处理</span></div><div class="line"><span class="keyword">for</span> i <span class="keyword">in</span> `seq 6 10`</div><div class="line"><span class="keyword">do</span></div><div class="line">    l=`sed -n <span class="string">"<span class="variable">$i</span>"</span>p 1.txt`</div><div class="line">    <span class="built_in">echo</span> <span class="variable">$l</span>|sed <span class="string">'s/[a-zA-Z]//g'</span></div><div class="line"><span class="keyword">done</span></div><div class="line"><span class="comment">##剩余的直接输出</span></div><div class="line"><span class="keyword">for</span> i <span class="keyword">in</span> `seq 11 <span class="variable">$nu</span>`</div><div class="line"><span class="keyword">do</span></div><div class="line">    sed -n <span class="string">"<span class="variable">$i</span>"</span>p 1.txt</div><div class="line"><span class="keyword">done</span></div><div class="line"><span class="comment">##若想把更改内容写入到1.txt，还需要把以上内容重定向到一个文本中，然后删除1.txt，再把刚刚重定向的文件更名为1.txt</span></div></pre></td></tr></table></figure>

	

	
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